(1) Field of Invention
This invention relates generally to cutting tools and methods for repairing ball valve seats. More particularly it relates to the repair of valve seats in hydraulic jacks.
(2) Description of Prior Art
There are generally two recognized methods for repairing valve seats in hydraulic jacks. One method involves reamers, where drills with beveled ends attempt to repair the valve by smoothing out the walls of the old seat. A second method involves the use of inserts. An insert containing a new seat is slipped in on top of the old seat and sealed by means of impact (see Freiheit '640). Neither of these recognized methods is foolproof, because it is difficult to remove all defects in the old walls with a reamer and inserts do not always form a tight seal. The net results in many cases are continued leaks and inefficient pumping action. The method and tool of the present invention provide a much more simple, direct and rapid means for accomplishing the repair. The design of the tool controls the depth and precision of the cut. The range of diameters permits essentially all known jacks to be repaired. If the steps of the method are followed precisely there is virtually no chance of a faulty repair job. Prior Art known to this inventor includes the following U.S. Pat. Nos:
______________________________________ 1,235,604 8/1917 Royle 2,069,153 1/1937 Konkle 2,289,065 7/1942 Oliver 2,587,980 3/1952 Doepker 3,260,139 7/1966 Sanborn 3,736,640 6/1973 Freiheit Re. 26,452 9/1968 Dearborn 3,991,456 11/1976 Lieser 4,395,169 7/1983 Kashiwagi et al ______________________________________